patch 8.2.2892: error message contains random characters

Problem:    Error message contains random characters.
Solution:   Pass the right pointer to error_white_both(). (closes #8272,
            closes #8263)
diff --git a/src/eval.c b/src/eval.c
index b5820b8..f75263d 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2934,7 +2934,7 @@
 	 */
 	if (evaluate && vim9script && !IS_WHITE_OR_NUL((*arg)[oplen]))
 	{
-	    error_white_both(p, oplen);
+	    error_white_both(*arg, oplen);
 	    clear_tv(rettv);
 	    return FAIL;
 	}